On the dyno, this Exorcist makes 902.1 horsepower (672.7 kilowatts) and 795.2 pound-feet (1,078.1 Newton-meters) of torque at the wheels. In comparison, the video from April 2017 showed the muscle car making 959.32 hp (715.36 kW) and 756.29 lb-ft (1,025.4 Nm).

Hennessey claims the Exorcist’s engine produces 1,000 hp (746 kW) and 883 lb-ft (1,197 Nm) of torque. Given the figures in the latest dyno run, this equates to driveline losses of 9.79 percent of the horsepower and 9.94 percent of the torque in a transition from the powerplant to the road.

The changes result in a muscle car that sounds completely different from a stock Camaro ZL1. The Exorcist makes a mighty roar that increases as the revs grow.

To turn the Camaro ZL1 into an Exorcist, Hennessey overhauls the stock powerplant. The 6.2-liter V8 receives a heavily revised valvetrain, including new camshafts, improved valve springs, revised valves, and ported cylinder heads. A high-flow supercharger and upgraded intercooler aid the forced induction part of the system. Stainless steel exhaust headers and midpipes, in addition to better flowing catalytic converters, to a better job of getting rid of the exhaust.